Recently, optical disk recorders for writing and storing video and audio digital data on an optical disk such as a DVD have become more and more popular. The targets of recording include a data stream representing a broadcast program and video and audio data streams that have been captured using a camcorder, for example. The user can write and store the data on a DVD in a randomly accessible state.
Optical disk recorders can write not only moving picture data streams but also still picture data on a DVD. If the user has shot a still picture using a digital still camera or a camcorder, the still picture data is written on a semiconductor memory card loaded there. Some optical disk recorders have a slot to load such a semiconductor memory card into the recorder. If the user removes a semiconductor memory card from a camcorder, for example, inserts the card into the slot, and then copies the still picture data onto a DVD that has been loaded in the optical disk recorder, the still picture data is stored on the DVD.
Regarding the techniques of writing still picture data on a storage medium, Design rule for Camera File system (DCF) standard was set and has become gradually known lately. The DCF standard defines the names and file formats of still picture files that can be written on a storage medium and a directory structure to store those files. For example, Patent Document No. 1 discloses the technique of bound-recording data compliant with the DCF standard. By establishing a directory and writing still picture data compliant with the DCF standard, the still picture data can always be read irrespective of the type of the storage medium and the manufacturer of the player.
As described above, not only moving picture data but also still picture data can be stored on a DVD. Thus, it would be very convenient for the user to make the contents of the data stored easily recognizable. That is why a lot of optical disk recorders provide some means for allowing the user to access his or her desired content very quickly by presenting either a thumbnail picture showing a scene of the moving picture data or still picture data in a reduced size on the menu screen that prompts the user to select a file to be read.    Patent Document No. 1: Japanese Patent Application Laid-Open Publication No. 2002-116946